Amid the elevated awareness of crisis in the face of global warming problems in recent years, vehicle transmission is required to provide higher efficiency, and efforts have been made for the development of technologies for expansion of the lockup area in an automatic transmission (AT) using a torque converter or compatibility of a continuously variable transmission with a vehicle of greater displacement. Against this backdrop, an automated MT (automatic manual transmission) has been developed to automate the clutch operation and gear change using the mechanism of a manual transmission of high transmission efficiency.
However, in the control method at the time of speed change based on the conventional MT, the drive torque is interrupted by the disengagement and engagement of the clutch, and this gives a sense of incompatibility to the driver.
In an effort to solve this problem, a new proposal has been produced of a torque assisted automated MT made of the automated MT equipped with a friction clutch (assist clutch) (See Japanese Patent Laid-Open No. Sho 61 (1986)-045163). In this torque assisted automated MT, the dog clutch prior to speed change is switched over to the assist clutch, and the assist clutch is then switched over to the dog clutch, whereby torque interruption is avoided.
In another proposal, two power transmission systems leading from the output shaft of the prime mover to the transmission output shaft are provided. This is a twin clutch type automated MT that has two clutches for switching between connection and disconnection of the input torque from each of the power transmission systems. In this twin clutch type automated MT, torque interruption is avoided by speed change from the gear of one of the power transmission systems to that of the other power transmission systems through the operation of switching between two clutches.